回车转TAB

        private void FrmItemDetailsAdd_KeyDown(object sender, KeyEventArgs e)
        {
            string keyCode = e.KeyCode.ToString();
            switch (keyCode)
            {
                case "Enter":
                case "Return":
                    if (this.ActiveControl is TextBox)
                    {
                        if (!((TextBox)this.ActiveControl).Multiline)
                        {
                            SendKeys.Send("{TAB}");
                        }
                    }
                    break;
            }
            switch (e.KeyValue)
            {
                case 116:
                    // 点击了F5按钮
                    this.FormOnLoad();
                    break;
            }
        }

   protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {       
            if (keyData == Keys.F5)
            {
                this.FormOnLoad();
            }

            if ((!(ActiveControl is Button)) &&
                (keyData == Keys.Up || keyData == Keys.Down || keyData == Keys.Enter))
            {
                if (keyData == Keys.Enter)
                {
                    System.Windows.Forms.SendKeys.Send("{TAB}");
                    return true;
                }
                if (keyData == Keys.Down)
                {
                    System.Windows.Forms.SendKeys.Send("{TAB}");
                }
                else
                {
                    SendKeys.Send("+{Tab}");
                }

                return true;
            }
            else
            {
                return base.ProcessCmdKey(ref msg, keyData);
            }
        }